An NMR spectrometer is an instrument which can analyze a sample by subjecting the sample to a very strong magnetic field. In a typical spectrometer, a sample is placed in a sample holder consisting of a very small diameter tubular container, which is supported by a generally cylindrical, lightweight, stopper-like support. The support is sized to slidably fit in a vertical shaft which extends down between the poles of the spectrometer magnet. An upwardly flowing air stream is provided in the shaft which is sufficiently strong to transport the sample holder between the top of the shaft and a sample locator positioned between the magnet poles and usually consisting of a constriction in the magnet shaft. In other words, the sample holder may be moved up and down within the shaft by the column of air in that shaft.
The sample holder is loaded into the spectrometer by placing the holder at the entrance to the magnet shaft where it is supported by the column of air in the shaft. Then, the air flow in the shaft is reduced to lower the sample holder down into the shaft to the sample locator where the sample in the holder is to be analyzed. Following the analysis, the air flow in the tube is increased to return the sample holder to the top of the magnet shaft where the holder will "float" on the escaping air until grasped and removed from the spectrometer.
Usually the sample holders are inserted into and removed from the spectrometer manually which requires the constant attendance of an operator. Successive holders may also be loaded and unloaded automatically using a robotic arm which emulates the manual loading and unloading operations. However, such mechanical arms are relatively complex and expensive. Furthermore, they occupy a relatively large amount of space. Also, existing robotic sample changers require extensive mounting and alignment procedures, as well as electronic interfacing with the spectrometer in order to operate properly.